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The difference bet the voltage actually reqd for an electrode reaction to occur & that expected thereotically, is termed as overvoltage Oxygen overvoltage on Platinum electrode is about 0.25V here u shud note overvoltage is diff for diff electrodes &for diff gases now let us use this overpot factor in deciding product of electrolysis .Rules to precdict pdt of electrolysis is as follows For anode reaction species having lower red pot is oxidised 2. For cathode reaction species having higher red pot is reduced. Take electrolysis of concentrated NaCl Na+ + Cl- for Cathode reaction H2O has higher red pot so pdt is not Na but H2 For anode reaction H2O has a value 1.23 & for Cl- itis1.36 it appers that H2O will get oxidised but Cl- get oxidised bec of overpot of O2 LIBERATION as movement of electrons is kinetically slow process req sm pot extra
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E-Store
its over potential
